The present invention relates to an insertion device for inserting into an eye an intraocular lens that is inserted instead of a crystalline lens after the crystalline lens is extracted because of cataract or inserted into an eye in order to cure abnormal refraction.
In current operations for cataract, the central portion of the anterior capsule of an eyeball is ablated, a clouded crystalline lens is removed by an ultrasonic suction apparatus, and then an artificial intraocular lens (hereinafter simply referred to as a lens) is placed in the position of the removed clouded crystalline lens. When placing the lens in the eyeball, an operation method for inserting the lens into the eyeball through a small incision by using the flexibility of the lens and thereby deforming the lens, e.g. folding the lens into a small shape is the mainstream.
In the case of an operation, an insertion device is frequently used which deforms a lens set in a main body of the device into a small shape while moving the lens in the main body of the device by a pushing shaft and pushes out the lens into the eye from a front end opening of an insertion cylinder (nozzle) inserted into the incision. This insertion device is used not only for the operation of cataract but also for a lens inserting operation for an eyesight correction medical treatment.
When the lens is inserted into an eye by using the insertion device, a viscoelastic material such as sodium hyaluronate is introduced into the main body of the insertion device as a lubricant so that the lens is smoothly moved and deformed in the insertion device (see Japanese Patent Laid-Open No. 2004-351196). Moreover, the viscoelastic material has a function of spreading the space of the anterior chamber of the eye into which the lens will be inserted by being introduced into the eye through the insertion cylinder.
Further, it has been recently required to use inexpensive physiologic saline in place of the viscoelastic material.
However, when the main body of the insertion device is constituted by a plurality of components assembled to each other, for example, when a lens setting portion in the main body has a divided structure or an openable and closable structure, a liquid such as a viscoelastic material or physiologic saline leaks from a gap created at the assembled portion. The leaking liquid makes the insertion device slippery or soils the periphery of the device.
In the case of a conventional operation, a liquid is introduced into the insertion device immediately before the operation, which takes time and places a heavy burden on an operator or an assistant.
Further, even if the liquid such as a viscoelastic material or physiologic saline is introduced into an eye, a large amount of liquid leaking from a gap between an edge of an incision in the eye and an insertion cylinder (an amount of leakage outside the eye) prevents an increase in ocular tension and sufficient inflation of the anterior chamber.
To a pushing shaft, an elastic member such as rubber is frequently mounted for preventing a lubricant introduced into the main body from leaking from between an inner peripheral surface of the main body and the pushing shaft, and providing proper resistance (sliding feeling) to an operation of the pushing shaft.
In the conventional insertion device, the elastic member is secured to one or a plurality of points close to each other on the pushing shaft, and moved relative to the main body with the operation of the pushing shaft. This cannot prevent the pushing shaft from being inclined radially with respect to the main body around a contact position between the elastic member and the main body in the operation of the pushing shaft.
However, if the pushing shaft is inclined with respect to the main body, the front end of the pushing shaft is not precisely brought into contact with the lens placed in the main body, which may prevent the lens from being properly pushed out.